1. Field of the Invention
The present invention relates to a well stimulation tool for oil and/or gas production. More specifically, the invention is a hydraulically-actuated propellant stimulation downhole tool for use in a hydrocarbon well.
2. Description of the Related Art
In hydrocarbon wells, fracturing (or “fracing”) is a technique used by well operators to create and/or extend a fracture from the wellbore deeper into the surrounding formation, thus increasing the surface area for formation fluids to flow into the well. Fracing may be done by either injecting fluids at high pressure (hydraulic fracturing), injecting fluids laced with round granular material (proppant fracturing), or using explosives to generate a high pressure and high speed gas flow (TNT or PETN up to 1,900,000 psi) and propellant stimulation.
Gas generating propellants have been utilized in lieu of hydraulic fracturing techniques as a more cost effective manner to create and propagate fractures in a subterranean formation. In accordance with conventional propellant stimulation techniques, a propellant is ignited to pressurize the perforated subterranean interval either simultaneous with or after the perforating step so as to propagate fractures therein.
For example, U.S. Pat. No. 5,775,426 (issued Jul. 7, 1998), which is incorporated by reference herein, describes a perforating apparatus wherein a shell of propellant material is positioned to substantially encircle a shaped charge. The propellant material is ignited due to shock, heat, and/or pressure generated from a detonated charge. Upon burning, the propellant material generates gases that clean perforations formed in the formation by detonation of the shaped charge and which extend fluid communication between the formation and the well bore.